1. Field of the Invention
The present invention relates to an airtight container, and a manufacturing method of an image displaying apparatus using the airtight container.
2. Description of the Related Art
As one example of a method of manufacturing an airtight glass envelope in which vacuum is maintained, there is a method in which a frit glass is used. In this method, the frit glass acting as a sealant is applied or set between respective glass members such as a face plate, a rear plate and an outer frame. Then, in such a state, the acquired subject matter is entered into a sealing furnace such as an electric furnace or the like or set on a hot plate (or interposed between the upper hot plate and the lower hot plate), and the entire subject matter (that is, the face plate, the rear plate and the outer frame) is heated up to a sealing temperature. Thus, since the frit glass is melted by this heating, the face plate and the outer frame are sealed together, and also the rear plate and the outer frame are sealed together. In conclusion, the glass envelope is formed by this method.
Besides, Japanese Patent Application Laid-Open No. 2000-149783 discloses a manufacturing method of a glass envelope. In this method, first, a sealing portion and its vicinity are heated by a sub local heater, and the entire glass envelope other than the sealing portion and its vicinity is heated by an assist heating hot plate heater. Then, a rear-plate frit glass constituting the sealing portion between a rear plate and an outer frame is locally heated up to a sealing temperature as being irradiated and scanned by a semiconductor laser. Subsequently, a face-plate frit glass constituting the sealing portion between a face plate and the outer frame is locally heated up to the sealing temperature as being irradiated and scanned by the semiconductor laser. That is, in Japanese Patent Application Laid-Open No. 2000-149783, such semiconductor laser irradiation is performed obliquely from the upper side of the outer frame, and the irradiation to the rear-plate frit glass is performed independently of the irradiation to the face-plate frit glass.
In the manufacturing method of the glass envelope as disclosed in Japanese Patent Application Laid-Open No. 2000-149783, since an incident energy beam is entered from the side of the outer frame, a part of the energy beam is totally reflected inside the outer frame. For this reason, since the energy does not reach the frit glass acting as a bonding material, there is a problem that it is difficult to effectively utilize the energy.
Further, the remainder of the incident energy beam entered from the side of the frit glass acting as the bonding material enlarges a temperature distribution of the bonding material. For this reason, there is a problem that bonding intensity decreases according as an area in which excellent bonding can be acquired decreases.
On the above premise, it is desirable to solve the above conventional problems. At the same time, it is also desirable to improve a “takt time” in the manufacture of the glass envelope.